202 Waheed et al. Int. J. Biosci. 2017 RESEARCH PAPER OPEN ACCESS Effects of pH on release of phosphorus from rock phosphate at different temperatures against the various time intervals involved Kashifa Naghma Waheed * , Nasreen Ijaz, Zehra Khatoon, Sikender Hayat, Umara Nuzhat Fisheries Research and Training Institute, Department of Fisheries, Lahore, Pakistan Key words: Rock phosphate, pH, Phosphate release http://dx.doi.org/10.12692/ijb/10.1.202-209 Article published on January 29, 2017 Abstract This study was undertaken to deduce the supply of phosphorous-phosphates from low grade Rock phosphates in aquatic media and to ascertain the best pH range out of several pH ranges so as to apply this research further on fish growths in ponds environment. In this regard, an attempt was made to study the efficiency of phosphorus released from Rock Phosphate at various temperatures and various pH ranges, i.e., 6-7, 7-8 and 8-9.The experiments were conducted during winter and summer season for a 96 hourly and then five weeks duration period. The phosphorus released concentrations were measured spectrophotometrically by ascorbic acid method. The results incurred, from the summer as well as from the winter experiments, revealed a maximum release of phosphorus fromT4treatmentsindicating that the higher pH (alkaline) range: 8-9 increased the rate of phosphorus release from Rock phosphate. The phosphate ranged between 0.06 to 0.40 mgL −1 values from all treatments during the study period with the highest at high temperature during summer season. Hence, Rock phosphate enriched soils could be an alternative and cheaper source of phosphorus fertilizer to utilize low-grade Rock phosphates efficiently for enhancing fish production for alkaline soils/ waters available all over the Punjab. * Corresponding Author: Kashifa Naghma Waheed  kashifanw@gmail.com International Journal of Biosciences | IJB | ISSN: 2220-6655 (Print), 2222-5234 (Online) http://www.innspub.net Vol. 10, No. 1, p. 202-209, 2017